"State and federal laws make discrimination based on certain protected categories, such as national origin, citizenship, age, marital status, disabilities, arrest and conviction record, military discharge status, race, gender, or pregnancy status, illegal.

Any question that asks a candidate to reveal information about such topics without the question having a job related basis will violate the various state and federal discrimination laws," Lori Adelson, a labor and employment attorney and partner with law firm Arnstein & Lehr, tells Business Insider.

"However, if the employer states questions so that they directly relate to specific occupational qualifications, then the questions may be legitimate. Clearly, the intent behind the question needs to be examined."

If you are asked any inappropriate questions, Adelson advises not to lie, but, instead, politely decline to answer.

"Could they not give you a job because of that? Sure. But if they do, they would be doing exactly what they're not supposed to do."

We compiled the following illegal interview questions that are often mistaken as appropriate from Adelson and Joan K. Ustin & Associates, a consultant firm specializing in human resources and organization development.

1. Have you ever been arrested?

An employer can't actually legally ask you about your arrest record, but they can ask if you've ever been convicted of a crime.

Depending on the state, a conviction record shouldn't automatically disqualify you for employment unless it substantially relates to your job. For example, if you've been convicted of statutory rape and you're applying for a teaching position, you will probably not get the job.

2. Are you married?

Although the interviewer may ask you this question to see how much time you'd be able to commit to your job, it's illegal because it reveals your marital status and can also reveal your sexual orientation.

3. What religious holidays do you practice?

Employers may want to ask you this to see if your lifestyle interferes with work schedules, but this question reveals your religion and that's illegal.

They can ask you if you're available to work on Sundays.

4. Do you have children?

It is unlawful to deny someone employment if they have children or if they are planning on having children in the future.

If the employer wants to find out how committed you will be to your job, they should ask questions about your work. For example, "What hours can you work?" or "Do you have responsibilities other than work that will interfere with specific job requirements such as traveling?"

5. What country are you from?

If you have an accent, this may seem like an innocent question, but keep in mind that it's illegal because it involves your national origin.

Employers can't legally inquire about your nationality, but they can ask if you're authorized to work in a certain country.

6. Is English your first language?

It's not the employers lawful right to know if a language is your first language or not.

In order to find out language proficiency, employers can ask you what other languages you read, speak, or write fluently.

7. Do you have any outstanding debt?

Employers have to have permission before asking about your credit history. Similar to a criminal background history, they can't disqualify you from employment unless it directly affects your ability to perform the position you're interviewing for.

Furthermore, they can't ask you how well you balance your personal finances or inquire about you owning property.

8. Do you socially drink?

Employers cannot ask about your drinking habits because it violates the Americans With Disabilities Act of 1990.

For example, if you're a recovering alcoholic, treatment of alcoholism is protected under this act and you don't have to disclose any disability information before landing an official job offer.

9. When was the last time you used illegal drugs?

It's illegal for employers to ask you about past drug addiction, but they can ask you if you're currently using illegal drugs.

A person who is currently using drugs is not protected under ADA.

For example, an employer may ask you: Do you currently use illegal drugs? What illegal drugs have you used in the last six months?

10. How long have you been working?

This question allows employers to guess your age which is unlawful. Similarly, they can't ask you what year you graduated from high school or college or even your birthday.

However, they can ask you how long you've been working in a certain industry.

11. What type of discharge did you receive in the military?

This is not appropriate for the interviewer to ask you, but they can ask what type of education, training, or work experience you've received while in the military.